The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 31, 1996
Filed:
Feb. 07, 1995
Ting Y Leung, San Jose, CA (US);
Mir H Pirahesh, San Jose, CA (US);
Michelle M Jou, San Jose, CA (US);
David E Simmen, San Jose, CA (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
A method and apparatus for optimizing SQL queries by propagating and exploiting column nullability. Column nullability is identified and propagated using a three-valued logic, wherein a column of a table can be identified nullability information is exploited to optimize query operations through transformations. In one aspect of the present invention, quantified predicates (such as '>ALL') are transformed into simple predicates involving singleton subqueries so that indexing can be exploited. In another aspect of the present invention, 'is not null' predicates are generated and pushed for certain aggregate queries. In still another aspect of the present invention, intersect operations are transformed into joins. The end result is that the present invention can significantly enhance the performance of the queries.
Data source: USPTO (United States Patent and Trademark Office) public patent records. Weekly synchronization. How IDiyas builds this profile